[PATCH v2 34/34] ARM: mmu64: Use two level pagetables in early code

[Sascha Hauer]

So far we used 1GiB sized sections in the early MMU setup. This has
the disadvantage that we can't use the MMU in early code when we
require a finer granularity. Rockchip for example keeps TF-A code
in the lower memory so the code just skipped MMU initialization.
Also we can't properly map the OP-TEE space at the end of SDRAM non
executable.

With this patch we now use two level page tables and can map with 4KiB
granularity.

The MMU setup in barebox proper changes as well. Instead of disabling
the MMU for reconfiguration we can now keep the MMU enabled and just
add the mappings for SDRAM banks not known to the early code.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 arch/arm/cpu/mmu_64.c | 97 +++++++++----------------------------------
 1 file changed, 20 insertions(+), 77 deletions(-)

diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
index d32eecf144..2f9b5098a3 100644
--- a/arch/arm/cpu/mmu_64.c
+++ b/arch/arm/cpu/mmu_64.c
@@ -22,7 +22,10 @@
 
 #include "mmu_64.h"
 
-static uint64_t *ttb;
+static uint64_t *get_ttb(void)
+{
+	return (uint64_t *)get_ttbr(current_el());
+}
 
 static void set_table(uint64_t *pt, uint64_t *table_addr)
 {
@@ -42,7 +45,7 @@ static uint64_t *alloc_pte(void)
 	if (idx * GRANULE_SIZE >= ARM_EARLY_PAGETABLE_SIZE)
 		return NULL;
 
-	return (void *)ttb + idx * GRANULE_SIZE;
+	return get_ttb() + idx * GRANULE_SIZE;
 }
 #else
 static uint64_t *alloc_pte(void)
@@ -63,7 +66,7 @@ static __maybe_unused uint64_t *find_pte(uint64_t addr)
 	uint64_t idx;
 	int i;
 
-	pte = ttb;
+	pte = get_ttb();
 
 	for (i = 0; i < 4; i++) {
 		block_shift = level2shift(i);
@@ -112,6 +115,7 @@ static void split_block(uint64_t *pte, int level)
 static void create_sections(uint64_t virt, uint64_t phys, uint64_t size,
 			    uint64_t attr)
 {
+	uint64_t *ttb = get_ttb();
 	uint64_t block_size;
 	uint64_t block_shift;
 	uint64_t *pte;
@@ -121,9 +125,6 @@ static void create_sections(uint64_t virt, uint64_t phys, uint64_t size,
 	uint64_t type;
 	int level;
 
-	if (!ttb)
-		arm_mmu_not_initialized_error();
-
 	addr = virt;
 
 	attr &= ~PTE_TYPE_MASK;
@@ -192,37 +193,23 @@ static void mmu_enable(void)
 void __mmu_init(bool mmu_on)
 {
 	struct memory_bank *bank;
-	unsigned int el;
-
-	if (mmu_on)
-		mmu_disable();
-
-	ttb = alloc_pte();
-	el = current_el();
-	set_ttbr_tcr_mair(el, (uint64_t)ttb, calc_tcr(el, BITS_PER_VA),
-			  MEMORY_ATTRIBUTES);
 
-	pr_debug("ttb: 0x%p\n", ttb);
-
-	/* create a flat mapping */
-	arch_remap_range(0, 1UL << (BITS_PER_VA - 1), MAP_UNCACHED);
-
-	/* Map sdram cached. */
 	for_each_memory_bank(bank) {
 		struct resource *rsv;
+		resource_size_t pos;
 
-		arch_remap_range((void *)bank->start, bank->size, MAP_CACHED);
+		pos = bank->start;
 
 		for_each_reserved_region(bank, rsv) {
-			arch_remap_range((void *)resource_first_page(rsv),
-					 resource_count_pages(rsv), MAP_UNCACHED);
+			arch_remap_range((void *)pos, rsv->start - pos, MAP_CACHED);
+			pos = rsv->end + 1;
 		}
+
+		arch_remap_range((void *)pos, bank->start + bank->size - pos, MAP_CACHED);
 	}
 
 	/* Make zero page faulting to catch NULL pointer derefs */
 	zero_page_faulting();
-
-	mmu_enable();
 }
 
 void mmu_disable(void)
@@ -256,42 +243,6 @@ void dma_flush_range(void *ptr, size_t size)
 	v8_flush_dcache_range(start, end);
 }
 
-static void early_create_sections(void *ttb, uint64_t virt, uint64_t phys,
-				  uint64_t size, uint64_t attr)
-{
-	uint64_t block_size;
-	uint64_t block_shift;
-	uint64_t *pte;
-	uint64_t idx;
-	uint64_t addr;
-	uint64_t *table;
-
-	addr = virt;
-
-	attr &= ~PTE_TYPE_MASK;
-
-	table = ttb;
-
-	while (1) {
-		block_shift = level2shift(1);
-		idx = (addr & level2mask(1)) >> block_shift;
-		block_size = (1ULL << block_shift);
-
-		pte = table + idx;
-
-		*pte = phys | attr | PTE_TYPE_BLOCK;
-
-		if (size < block_size)
-			break;
-
-		addr += block_size;
-		phys += block_size;
-		size -= block_size;
-	}
-}
-
-#define EARLY_BITS_PER_VA 39
-
 void mmu_early_enable(unsigned long membase, unsigned long memsize)
 {
 	int el;
@@ -299,24 +250,16 @@ void mmu_early_enable(unsigned long membase, unsigned long memsize)
 
 	pr_debug("enabling MMU, ttb @ 0x%08lx\n", ttb);
 
-	/*
-	 * For the early code we only create level 1 pagetables which only
-	 * allow for a 1GiB granularity. If our membase is not aligned to that
-	 * bail out without enabling the MMU.
-	 */
-	if (membase & ((1ULL << level2shift(1)) - 1))
-		return;
+	el = current_el();
+	set_ttbr_tcr_mair(el, ttb, calc_tcr(el, BITS_PER_VA), MEMORY_ATTRIBUTES);
 
 	memset((void *)ttb, 0, GRANULE_SIZE);
 
-	el = current_el();
-	set_ttbr_tcr_mair(el, ttb, calc_tcr(el, EARLY_BITS_PER_VA), MEMORY_ATTRIBUTES);
-	early_create_sections((void *)ttb, 0, 0, 1UL << (EARLY_BITS_PER_VA - 1),
-			attrs_uncached_mem());
-	early_create_sections((void *)ttb, membase, membase, memsize - OPTEE_SIZE, CACHED_MEM);
-	tlb_invalidate();
-	isb();
-	set_cr(get_cr() | CR_M);
+	arch_remap_range(0, 1UL << (BITS_PER_VA - 1), MAP_UNCACHED);
+	arch_remap_range((void *)membase, memsize - OPTEE_SIZE, MAP_CACHED);
+	arch_remap_range((void *)membase + memsize - OPTEE_SIZE, OPTEE_SIZE, MAP_FAULT);
+
+	mmu_enable();
 }
 
 void mmu_early_disable(void)
-- 
2.39.2